# Questions tagged [geophysics]

Geophysics is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment.

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### How much heat is transported from the interior to the surface in the form of hydration enthalpy?

Heat is transferred from the interior to the surface through several methods. One is simply the conduction of sensible heat through the crust - I would guess this accounts for most of it. But some is ...
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### What are the ground motion prediction equations for 3-D ruptures?

Ground motion prediction equations (GMPEs) estimate ground motion at any given site due to an earthquake at a distance. There are many such equations, each with different parameters. Can somebody ...
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### In quasi-geostrophic frontogenesis, what happens if the potential vorticity is negative?

In particular, what happens if the Sawyer–Eliassen equation cannot be solved? I know that a condition for the Sawyer–Eliassen equation to have a solution is $F^2 N^2 - S^4 >0$, which means that the ...
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### Where can I find an anisotropic PREM-like model for Earth's interior?

So, I just discovered PREM (the Preliminary reference Earth model) which models the density distribution of matter inside the Earth to any depth. The PREM is very convenient but since it only depends ...
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### High-resolution laterolog array tool

Does anybody know if it is necessary to apply corrections to the reading given by this logging tool? Corrections such as bed thickness, borehole diameter, invasion, etc.? If so, is there anywhere I ...
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### How much does the Earth's center of mass move around?

How much does the Earth's center of mass move around relative to the most stationary objects on the surface? I'm wondering whether the molten outer core has enough asymmetry to move the center of ...
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### How do the Andes get so high?

I'm interested in the limiting factors on the height of mountains. There is a very good explanation at https://www.quora.com/How-tall-can-a-mountain-become-on-Earth-Neil-deGrasse-Tyson-says-Mount-...
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### How do you choose appropriate parameters for a lowpass filter when filtering a Bouguer anomaly?

I am trying to filter my Bouguer anomaly data to remove the short wavelength features. I have created a lowpass filter to achieve this, but I am wondering how I can more objectively choose my cutoff ...
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### How do I generate a Moho depth model from seismic refraction data?

There are several permanent seismograph stations in Eastern Canada that have been recording arrival times for over 25 years. Using refracted Pn arrival times from natural earthquakes I would like to ...
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### Over what scales can we begin to apply fluid dynamics to accurately model properties of the mantle?

Over what size temporal/spatial scales do geophysicists and geodynamicists begin to apply fluid dynamics to model the mantle rather than elastic/plastic deformation theory?
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### How much would the ground be displaced in a magnitude 11 earthquake?

In a magnitude 5 earthquake, the ground shakes violently and it's often impossible to stay upright. This is caused by about 50-120 cm of displacement of the ground. But how much would the ground move ...
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### Hypothetically, in the near future, could gas hydrate pingos erupt?

Could gas hydrate pingos erupt? If so, how quickly? And how much CH4 could they release? I'm sorry if the questions sounds silly. I'm new here and I don't know much about gas hydrates and oceanography....
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### Did the Three Gorges Dam shift the North Pole by 2 cm?

Numerous sources repeat that, apart from slowing down the rotation of the globe, the Three Gorges Dam caused the geographic pole to shift by 2 cm. For example: https://blog.prv-engineering.co.uk/...
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### How long for tectonic plates to develop from a planetary, molten planetary surface?

On Earth or an Earth-like planet, how long does it take for a molten surface to solidify into planetary crust, and how long does it take for that crust to develop into tectonic plates?
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### Cratonization - how did the Archean cratons form?

Before the onset of modern style plate tectonics and the Wilson cycles in the late Archean, it is thought that smaller units of continental crust, called cratons, roamed the oceanic crust over a more ...
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### Can an igneous rock have a Vp of less than 1000 m/s and need blasting to excavate?

I have run a 60 m refraction seismic line on a mountain summit. The environment was noisy (wind would be the principal agent) and quite difficult to pick first arrivals. It resulted in 800 m/s. A ...
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### Is it possible for Mexico to have a magnitude 9 earthquake?

Everyone has heard of the Cascadia Subduction Zone and the potential threat it poses. However, I have heard nothing about The Cocos Subduction Zone, even though it caused a devastating earthquake over ...
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### Do northern lights (aurora borealis) show the same visual activity all along their visible latitude range?

Probability aside regarding their visibility (I did read on Neil Davies Aurora watcher's handbook that probability is highest in the middle of their latitude range called aurora oval, lowering both ...
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### transition elastic deformation to flow

Let's assume a small (and smooth) vertical deformation of the seabed. If done quickly, I can consider it a vertical force generating an acoustic wave in the water, where every particle of water ...
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### Difference between landslide waves and earth quake waves

I am new to this field, recently started working on landslide monitoring mainly in signal processing part. I have the following questions? 1.Will each land slide and every vibration have p wave, s ...
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### How to calculate seismic moment from seismograms?

I was told that Seismic moment is determined by the observed spectral levels of the receiving waves. But I don't quite understand what it means. How is this done in practice? Do you need ...
292 views

### measuring fracture length and width using PKN and KGD models for hydraulic fracturing?

I am trying to understand PKN and KGD models for hydraulic fracturing. I am wondering why equations for fracture width and length does not include 'breakdown pressure' (pressure at which fracture ...
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### Phase of S2 constituent in tidal prediction

I ran the ETERNA code for the prediction of tidal gravity at some station. Then I use Fourier analysis to recover the amplitude and phase of the S2 constituent. As I understand, the phase of the S2 ...
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### When will the Earth lose its magnetic field?

Mars lost its magnetic field 4.5 billion years ago according to this article: Mars lost its global magnetic field during the time of this heightened activity. After 500 million years, the Martian ...
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### Quality control in Seismic Acquisition - shot offset shift

I have a problem with seismic data where the minimum offset of the shot is not centered at the nearest receiver, this shift can be for 3 traces 2 or one and maybe more in the two sides !! So is there ...
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### Conversion of SEG-Y relative to MSL

I am working on the conversion of CSF file from SonarWiz into SEG-Y data. However, it comes back always related to the Sensor depth/altitude and never to the MSL. I have tried changing the bytes from ...
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### Is there a way to convert from Dip direction to Strike direction?

I have some set of recorded data in dip direction/dip format. I wish to transform then to strike/dip. I am currently having a hard time imagining how to convert from dip direction to strike direction. ...
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I had this albedo conversion written down: $$\alpha = 0.53\alpha_{VIS}+0.47\alpha_{NIR}$$ I had on my notes that this equation was form Collins et al (2002). However, I cannot find where this came ...
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### Construction of a drift curve in the well tie calibration and how to interpret it?. Sonic calibration vs checkshot calibration

Good afternoon. Inside the creation of the synthetic seismogram some softwares have the option to run what is called "sonic calibration" or "checkshot calibration". I have some questions: 1)why some ...
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### Geo-Spherical shape of Earth

I know that the best possible approximation of the shape of earth is an oblate sphere. But people also call it as geo-spherical shape of the Earth. What is the meaning of geospherical shape? Does this ...
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### Equatorial Bulge and its implications on the climate

How much of the variance in the climate is due to the equatorial bulge and how much sun radiation do we lose due to the equatorial bulge? I am interested in the variance both through time and ...
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### Finding out actual dip and dip direction of refractor

We have two traveltive curves for first arrivals (direct and refracted) from a dipping refractor in the forward and reverse directions along a profile line. my question is: Is there a logical way (non-...
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### Determining the spatial orientation of a fault given ground acceleration magnitude in different directions

Accelerographs measure ground acceleration in three different components of motion: east-west, north-south, and vertically (up-down). I know that fault orientation is important here, so let's say we ...
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### Which is naturally more radioactive: a tertiary or cretaceous sandstone? Why?

I've come across this question in a Petrophysics exercise regarding the Gamma Ray well logging. And I don't know how to solve it. This is the "believed" AFAIK session Natural radioactivity ...
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### Which wavelengths is limestone most transparent to?

I think of the non-ionizing range, e.g. Terahertz or Radio. Limestone clearly is transparent to x-ray or gamma but thats not what i am asking for. Natural to low ranges of porosity/water content ...
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### Do living things have a magnetic field capable of any level of solar protection?

I understand how anything with an electrical current have a magnetic field including living things. Would a densely populated rain forest or jungle have enough combined magnetic field among the living ...
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### Is there a formally-defined converse of a Prominence Walk?

My question was inspired by this one - in particular, the subtopic of pumping water from the ocean to the below-sea-level basins to deal with rising sea levels (spoiler: it's horribly infeasible and ...
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### Easiest way to find the water table under my feet

I had burnt my finger by digging an empty well and spending my hard-earned money in vain. I then started to study about the resistivity method for finding underground details. But I have many doubts ...
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### Why does the lithosphere thickness vary within a short distance?

Can someone explain why the lithosphere thickness varies within a short distance (30-100km) at the same upper mantle viscosity around the polar region? And what is the behaviour of a thin (20-70km) ...
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### Interpretation of horizon display

I am currently working on a project that involves using seismic attributes as input parameters in a neural network for estimation of porosity and permeability for a reservoir. Now, I need to correlate ...
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### How can this fountain of (hot?) water coming out of the Earth arise?

In this video from min. 7:00 is after digging in the Earth a fountain created of water. Is this due to the pressure of the water in the Earth, if so how did it get there and how did it get such a high ...
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### Why is the average 1 Bar temperature on planets with a thick atmosphere proportional to the distance of the sun?

The temperature of a planetary body in space varies with the fourth-root of the power incident upon it, this is derived from the Stefan-Boltzmann Law. This is understandable when applied to a black ...
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### Differentiate correlation of between depth and bouguer anomaly

Assume we measure bouguer anomaly (g) and depth (H) of the certain horizon through a profile at each point. Based on data we get a correlation between H and g and express it with a polynomial equation ...